Power Converter Current Estimation via Diode On-Time
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Solution Overview
Problem
Existing switching power conversion circuits require dedicated pins for feedback signals, leading to increased silicon area and cost due to the use of analog circuits, and external switches occupy additional space and resources.
Innovation Solution
A power conversion circuit that includes a voltage estimation circuit and a current estimation circuit to generate pulse width modulated signals based on output voltage and current estimates, reducing the need for extra pins and using integrated silicon chips with MOS devices, allowing for boost, buck, or buck-boost configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated pins are used for feedback signals in switching power conversion circuits, then output monitoring is achieved, but silicon area and circuit cost increase
Solution Approach 1:
The patent combines multiple functions into existing circuit nodes. The feedback signal is obtained by sampling the voltage at the switch-inductor node, which already exists in the circuit. This merges the monitoring function with the existing power conversion circuitry, eliminating the need for dedicated feedback pins and reducing silicon area while maintaining reliable output monitoring through the existing circuit topology
Solution Approach 2:
The circuit uses its own internal nodes and signals for monitoring purposes. The voltage at the switch-inductor node, which is already present due to the switching operation, is directly utilized for feedback without requiring external monitoring components or dedicated pins. The circuit serves its own monitoring needs using resources already available within its operation
2Ease of manufacture
If analog circuits are used for power conversion, then power conversion function is achieved, but silicon area and manufacturing cost increase
Solution Approach 1:
The patent replaces traditional analog circuit implementations with a digital control approach. A microcontroller or digital logic circuit samples the voltage at the switch-inductor node and generates PWM control signals based on digital processing. This substitution of digital for analog circuitry reduces silicon area and simplifies manufacturing while maintaining the power conversion function through digital pulse width modulation
3Ease of operation
If external switches are used in power conversion circuits, then switching function is achieved, but external space and system cost increase
Solution Approach 1:
The patent integrates the switch control function directly into the integrated circuit. The microcontroller or digital logic generates PWM signals that directly control the switching element, combining the control and switching functions within the same package. This eliminates the need for external switches and reduces external space requirements while maintaining full switching functionality through integrated control
Data Source
AI summary
A controller for a power conversion circuit that includes an inductor, a diode, and a switch. The controller includes a counter configured to determine, based on a first voltage input to the inductor, an on-time of the diode. The on-time of the diode corresponds to an amount of time that the diode is conducting a first current to a load of the power conversion circuit. A current estimation circuit configured to estimate, based on the on-time of the diode and an on-time of the switch, an output current of the power conversion circuit. The on-time of the switch corresponds to an amount of time that the switch is conducting a second current. A pulse width modulator is configured to provide, based on the estimated output current, a gate drive signal to the switch. The gate drive signal selectively transitions the switch between an on state and an off state.